Phase comparison monopulse angle estimation is a well known technique for measuring angle of arrival of a signal in a radar or other radio frequency electromagnetic sensor. To use this technique, the receiving antenna is typically divided into two halves. The angle of arrival is a function of the ratio of the difference signal (created by subtracting the signal from the two halves) divided by the sum signal (created by adding the two halves). This value is known as the monopulse discriminant.
Generally, the algorithm that performs the angle estimation using the monopulse discriminant relies on the assumption that the value of the monopulse discriminant does not substantially vary as a function of the frequencies that make up the signal. However, this assumption does not hold true for wideband or spread spectrum waveforms or signals when they are measured by an electronically scanned phased array antenna.